Interactions Between Copper and Chlorine Disinfectants: Chlorine Decay, Chloramine Decay and Copper Pitting

Interactions between copper and chlorine disinfectants were examined from the perspective of disinfectant decay and copper pitting corrosion. Sparingly soluble cupric hydroxide catalyzed the rapid decay of free chlorine, which in turn, led to production of less soluble and more crystalline phases of cupric hydroxide. The catalytic activity of the cupric hydroxide was retained over multiple cycles of chlorine dosing. Experiments with chloramine revealed that copper species could also trigger rapid loss of chloramine disinfectant. In copper pipes, loss of free chlorine and chloramine were both rapid during stagnation. Reactivity of the copper to the disinfectants was retained for weeks. Phosphate tended to decrease the reactivity between the copper pipe and chlorine disinfectants. A novel, inexpensive and real-time test to monitor copper pitting corrosion was developed. In a normal pipe, it is not possible to measure the electron flow or pitting current from the pit anode to the cathode. But a new method was developed that can form an active pit on the tip of a copper wire, which in turn, allows the pitting current to be measured. Preliminary experiments presented herein have proven that this technique has promise in at least one water condition known to cause pitting. The method also quickly predicted that high levels of orthophosphate could stop pitting attack in this water, whereas low levels would tend to worsen pitting. Future research should be conducted to examine this technique in greater detail.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Environmental Planning

Department dc:contributor.department

Environmental Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2005

Author dc:creator

• Nguyen, Caroline Kimmy

Chair dc:contributor.committeechair

• Edwards, Marc A.

Committee members dc:contributor.committeemember

• Dietrich, Andrea M.
• Vikesland, Peter J.

• Flow
• Aluminum
• Corrosion
• Chloramine
• Chlorine
• Pitting
• Copper

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

etd-11122005-155748

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/35674